41 = PCM detected a lean condition when closed loop was commanded on. Most common cause is a vacuum leak, as indicated by the hissing noise. Take the IC off and have a look.

Coolant smell is unrelated to the code 41. Check the water lines to the turbo and heater lines that run along the valve cover while you have the IC off. May need to pressurize the cooling system to find the leak.

On the vacuum T, there is a line that branches off and it has a "T" on it, but it's not connected to anything and it isn't plugged. The transmission shifts very hard...so the "T" must be for "Transmission"!

Never the two shall meet. Separated systems. Any chance the first check was with a cold trans and the second check was with the trans warm? Temperature can make some degree of difference in the dipstick reading.